Molds and mycotoxins

Here is a sneak preview of the forthcoming book Current Therapy in Equine Medicine, 5th Edition. The following chapter on Molds and Mycotoxins is by Mike Murphy.     

对霉菌毒素病的担忧将继续

<正>2009年美国多雨的天气引发了人们对霉菌毒素污染的担忧,当将玉米运送至存储的谷仓时水分含量高达20%,并且在干燥后重量明显变低,说明玉米的质量较差。对仓储公司和乙醇生产厂的调查显示,玉米中的呕吐毒素(DON)含量达到了令人无法接受的水平,此外还含有伏马菌素和单端孢霉烯族毒素类,偶见黄曲霉毒素。     

动物霉菌毒素中毒的研究

自从1960年英国10万火鸡X病爆发（即黄曲霉毒素中毒）,世界开始注重对霉菌毒素中毒的彻底调查。现在已经知道了许多霉菌毒素,如T-2毒素、赭曲霉毒素、呕吐毒素、串珠镰孢菌毒素、玉米赤霉烯酮和桔霉素也都存在于饲料原料和配合饲料中。霉菌毒素的广泛分布可能是由于：①改进分析程序,提高了霉菌毒素检测的灵敏性;②添加副产品和替代饲料原料来降低饲料成本,这也可能使霉菌毒素的含量提高;③全球气候条件的变化也有助于霉菌的生长,产生霉菌毒素;④畜禽日粮中的成分来源于不同气候条件下生长的谷物;⑤全球贸易的开通,饲料原料在生长、储存和运输中而受到不同程度的损害。     

猪霉菌感染及毒素中毒的发生原因

真菌在侵染农作物、饲草、饲料时产生的有毒代谢物能引起动物生长发育迟缓,免疫力下降,器官机能障碍,导致人畜急、慢性中毒,甚至死亡;致畸、致癌、致突变。这些真菌包括担子菌（如毒蘑菇）、毛霉、青霉、镰孢霉、曲霉等。众多畜牧业人士认为,当前霉菌毒素在我国乃至世界养猪业中危害巨大,且越来越呈现出广泛的、严重的破坏性。     

Granulocytopaenia and thrombocytopaenia in dairy cattle--a suspected mycotoxicosis

During a 6-week period, 22 Dairy Shorthorn cows and heifers died with granulocytopaenia and thrombocytopaenia. Clinical signs observed in the affected animals included increased salivation, pyrexia, depression, rumenal stasis, bilateral epistaxis, melaena, increased bleeding after removal of retained foetal membranes and rapid weight loss. Despite intensive antibiotic and vitamin K therapy and blood transfusions, all affected animals died. The aetiological agent, thought to be a fungal toxin, could not be isolated from post mortem specimens or pasture samples.     

Zearalenone and deoxynivalenol mycotoxicosis in dairy cattle herds

Mycotoxin contaminations pose a growing problem in animal production from the economic and toxicological point of view. Clinical symptoms of mycotoxicosis are relatively unspecific, making the disease difficult to diagnose. This study presents a clinical case of dairy cattle infected with natural mycotoxins produced by fungi of the genus Fusarium (zearalenone [ZEA] and deoxynivalenol [DON]) in eastern Poland. In dead and infected cows, the presence of ZEA and DON was determined in the blood serum, significant changes were observed in blood morphological and biochemical profiles, extravasations and bowel inflammations were also observed. The results reported testify to an acute autoimmune process in the intestines as well as immunosuppression.     

Cyclopiazonic acid mycotoxicosis in the dog

The subacute toxic effects of cyclopiazonic acid (CPA; given orally) were characterized in the dog (CPA was purified from cultures of Aspergillus flavus). Four groups of dogs were given CPA in gelatin capsules for 90 days at the following dosage levels: 0.05, 0.25, 0.5, and 1.0 mg/kg of body weight; a 5th group was used as controls. All dogs administered the 0.5 and 1.0 mg of CPA/kg dosages and 1 dog given the 0.25 mg of CPA/kg dosage died or were humanely killed before the scheduled termination of the study. Clinical signs of intoxication appeared 2 to 44 days after dosing was started and consisted of anorexia and, in 1 to 2 days, vomiting, diarrhea, pyrexia, dehydration, weight loss, and CNS depression. Grossly, the entire alimentary tract had diffuse hyperemia with focal areas of hemorrhage and ulceration. Other lesions were renal infarcts, necrotizing epididymitis, and ulcerative dermatitis. Microscopic lesions included ulceration, necrosis, vasculitis, lymphoid necrosis, karyomegaly in several organs, and decreased mitotic activity in intestinal crypt epithelium. Ulcerative and necrotic lesions were usually associated with vascular lesions. Clinical pathologic changes were leukocytosis, neutrophilia, lymphopenia, monocytosis, and increased serum alkaline phosphatase activity.     

真菌毒素的污染、危害及其检测技术

真菌毒素是农产品及饲料的主要污染源之一,本文阐述了常见真菌毒素的种类,包括黄曲霉毒素、脱氧雪腐镰刀菌烯醇、玉米赤霉烯酮、伏马菌素以及赭曲霉毒素等;分析了它们在农产品及饲料中的污染情况以及对人和动物的危害性;并对真菌毒素检测技术进行了简要介绍。     

镰孢霉菌的侵染规律、单端孢霉烯族毒素形成及调控机制

镰孢霉菌是一类数量大、种类繁多的真菌。它是农作物的重要病原体,可引起多种农作物腐烂和枯萎病,其中以小麦头痂病和玉米穗腐病最为普遍。镰孢霉菌代谢所产生的霉菌毒素也会污染农产品,其中单端孢霉烯族毒素污染粮食和饲料的问题非常普遍,是食品安全的重大威胁。单端孢霉烯族毒素对谷物特别是玉米和小麦的污染已成为一个全球性的问题,每年对种植业和养殖业造成巨大的经济损失。镰孢霉菌污染农作物以及霉菌毒素的产生是一个具有连续效应的过程,对镰孢霉菌的生长条件,侵染机制及毒素生成规律的研究有助于找到解决这一问题的对策。文章对镰孢霉菌侵染植物的规律,霉菌毒素形成过程以及调控技术加以综述。     

Fumonisin mycotoxicosis in broilers: performance and pathology.

Fusarium moniliforme culture material containing fumonisin B1 at 300 mg/kg was incorporated into a broiler starter ration and fed ad libitum to 1-day-old broiler chicks for 2 weeks in two experiments. Clinical features of the disease produced included diarrhea, a 19% reduction in body weight, a 30% increase in relative liver weight, and a worsening of feed conversion by 20 points at 2 weeks of age. Histologically, chicks fed fumonisin had multifocal hepatic necrosis, biliary hyperplasia, muscle necrosis, intestinal goblet-cell hyperplasia, and rickets. Simultaneous feeding of 0.5% aluminosilicate had no effect on the clinical disease or lesions. The clinical disease and lesions induced mimicked those of a viral enteritis.     

Citrinin mycotoxicosis in the rabbit: ultrastructural alterations

Citrinin was given to rabbits as a single oral dose of 120 or 67 mg/kg. Rabbits were killed at 4, 6, 8, 10, and 12 hours post dosing, and the kidneys were fixed by intravascular perfusion. Ultrastructural alterations were evident by 4 hours after treatment. In the proximal tubule, alterations were brush border disruption, cytoplasmic rarefaction, and swelling of interdigitating processes. At higher doses, mitochondria were condensed and distorted. Medullary and straight cortical distal tubules had marked distention of the intercellular spaces and disorganization of interdigitating processes. Changes in cortical and outer medullary collecting ducts were similar but less severe. Renal alterations were suggestive of damage to membrane structure and/or transport functions and interference with cellular bioenergetics. Leukocytic infiltration was associated with damaged tubules indicating a contribution of inflammation to the development of the lesions.     

青贮饲料中霉菌毒素的产生、毒性作用及脱毒研究进展

青贮饲料是反刍动物日粮中重要的组成部分,但青贮饲料在收获前、发酵期间及青贮完成后都会受到多种霉菌毒素污染.反刍动物摄入霉菌毒素后会对其健康和生产性能产生不利影响,并对食品安全及人类健康构成威胁.青贮饲料中优势霉菌包括镰刀菌属(Fusarium)、曲霉属(Aspergillus)、青霉属(Penicillium)和链格孢...     

Presumptive tremorgenic mycotoxicosis in a dog in New Zealand, after eating mouldy walnuts

CASE HISTORY: A 1-year-old, intact male Labrador-cross dog vomited after eating walnuts that had been on the ground for 5 months. The dog then developed tremors, ataxia, increased salivation, and hyperaesthesia. CLINICAL FINDINGS: The dog had marked generalised tremors, ataxia and a temperature of 39.9 degrees C. Both pupils were of normal size and normally responsive to light. Vomiting was induced, and walnut shell was visible in the vomitus. DIAGNOSIS: Due to the sudden onset of tremors, lack of exposure to other convulsive toxins, and the evidence of ingestion of walnuts, the provisional diagnosis was tremorgenic mycotoxicosis. The dog was treated symptomatically, and made a full recovery over 18 hours. Tremorgenic mycotoxins were detected within walnuts collected from the dog's environment. CLINICAL RELEVANCE: Fungi that produce tremorgenic mycotoxins are present in New Zealand. Intoxication should be suspected in dogs that suddenly develop muscle tremors, especially if there is a history of ingestion of mouldy food 2-3 hours prior to the development of tremors.     

Adrenal cortical necrosis caused by T-2 mycotoxicosis in female, but not male, mice

Experimentally, adrenal cortical parenchymal cell necrosis was induced by T-2 mycotoxin in female, but not male, mice. The lesion occurred in the adrenal glands in 11 of 11 female and 0 of 10 male mice given a nose-only aerosol exposure to T-2 mycotoxin. The necrosis, restricted to the zona fasciculata, began at the X zone interface and extended peripherally to involve 15% to 70% of the zone. Both light and transmission electron microscopies were used to determine whether the cellular and subcellular damage involved parenchymal cells of the zona fasciculata. Extensive necrosis of cortical thymocytes and necrosis of lymphoid cells in follicles of the spleen, lymph nodes, and intestine-associated lymphoid tissue were observed in both sexes. This is the first report to describe adrenal gland necrosis associated with exposure to T-2 mycotoxin.     

Morphology and ultrastructure of small intestine mucosa in gilts with zearalenone mycotoxicosis

Zearalenone (ZEA) is a mycotoxin produced by Fusarium. It evokes disruptions in sex cycle and changes in the morphology of the reproductive organs in pigs. The morphology and ultrastructure of the small intestine mucosa were assessed after the course of the experimental zearalenone mycotoxicosis. During the experiment, pigs were fed feed containing low doses of ZEA. The experiment lasted 7 days and it was carried out on sexually immature gilts that were divided into 3 groups: control group (C) and 2 experimental groups (E1, E2; n=8). Groups E1 and E2 were given ZEA every day at a dose of 200 and 400 microg/kg b.w. The samples of tissues were taken for examinations after the slaughter on the last day of the experiment. No significant changes in the morphology of the intestinal mucosa were found in the experimental animals. Increased activity of the goblet cells and high content of mucinogen vesicles, lymphocytic infiltration, increased activity of endocrine cells and the presence of Paneth cells on the bottom of intestinal crypts, which sugest mobilisation of the local defence mechanisms in the intestinal mucosa, were obseved in group E2.